The present invention is related to a zoom lens in which the magnification variation range as employed in an ordinarily used zoom lens is further enlarged and at the same time the magnification variation with an enlarged ranged can be consecutively done.
An ordinary zoom lens consists of a zoom part to determine the variation ratio of focal distance and a relay part to determine the variation range of focal distance, and has for example, zooming range of 50 mm to 500 mm.
However, there are such cases that zooming range of 100 mm to 1000 mm is desired during photographing, and at that time what is ordinarily done is to replace a relay part or to add a magnifying lens system in front of the zoom part or between the zoom part and the relay part. But such method has disadvantages that replacing of the relay part or mounting of the magnifying lens system takes time, and further the photographing image is cut out in a course of photographing when said parts are mounted.
Contrary to the above art, a technical thought that a relay part is replaced with another zoom lens so that the front zoom part with M times power and the rear zoom part with N times power are connected together to obtain a zoom lens with M.times. N times power has been known for example by the Japanese Utility Model Pat. No. Sho 40-2871.